The present invention relates to the integrated circuits, and in particular, to transformers and a system and method for analyzing the same.
Transformers are widely used in electrical and electronic engineering for the purpose of voltage, signal or impedance transformation. In high frequency integrated circuits or microwave monolithic integrated circuits (MMICs), transformers are usually used in low-noise amplifiers (LNA), doubly-balanced mixers, or voltage-controlled oscillators (VCO). More particularly, coplanar microstrip, stripline couplers, or coplanar transformers are commonly used in applications where signals need to be coupled at different voltage or phase levels or the impedance of a terminator needs to be transformed to another level. Typical designs for such applications involve transformers having primary and secondary windings that are configured on the same plane. Although operable, these typical designs of coplanar transformers are found to occupy a large area of a chip on which they are fabricated, thus, leading to an inefficient manufacturing process.
The present invention provides a vertical transformer that comprises a primary and a secondary winding, wherein one winding is positioned on a first plane, and the other winding is positioned on a second plane. The primary and secondary windings are separated by a dielectric substrate. In one embodiment, the primary and secondary windings are configured to use the same ground reference, and terminals in the center of each winding are connected to the ground reference by a via hole to form an in-phase transformer. In a second embodiment, a center terminal of one winding and an outbound terminal of the other winding are connected to the ground reference to form an opposite-phase transformer. In the second embodiment, a dielectric substrate is positioned between one of the windings and a ground plane.